package src;

/**
 * Created by dell on 2017/7/25.
 */
public class ZhengZe {
    public static void main(String[] args) {
        String st="hello , java!";
        System.out.println(st.replaceFirst("\\w*","0"));
        System.out.println(st.replaceFirst("\\w*?","0"));
    }
}
